1. Field of the Invention
The invention is in the field of small weapon sighting optics, and specifically to a periscopic eyepiece attachment for moving the line-of-sight of a telescopic night mounted on a small caliber weapon to the line-of-sight of the iron day sights which are always formed as integral part of the weapon for daytime use. The shooter can maintain a proper cheek weld on the weapon stock, as taught in small weapon training for achieving high accuracy of target strikes, whether firing the weapon using either the iron day sights or the night sight mounted upon the weapon.
2. Description of prior art.
Most all telescopic night sights are mounted over the receiver of small caliber weapons and above the iron sights which are used for zeroing the weapon during the day. The large diameter of the telescopic night sight's objective lens forces the shooter to raise his head to an unnatural position above his "cheek weld", i.e. above where the shooter's cheek would normally be against the weapon stock while viewing along the line-of-sight of the iron sights. The unnatural position of the shooter's head, and other human factor problems, become even more pronounced since the present telescopic night sights have increasingly larger diameter objectives to provide higher magnification.
Iron day sight placement and cheek weld formed on a particular weapon are the cumulative result of human factor considerations in the design of that weapon. It is therefore important that the shooter acquire the same natural eye position regardless of the sight being used on the weapon. The U.S. Army NA/PVS-4 starlight scope, presently being used, is one good example of the human factors problem. When this night vision scope is mounted on the U.S. Army M14 or M16 rifle, the eyepiece of the scope is about 21/4 inches above the line-of-sight of the iron sights. This distance prevents the shooter from maintaining the proper cheek weld and therefore adversely affects the shooter's accuracy. Most of all the day scopes are also mounted over the weapon receiver upon which the iron sights are attached. These days scopes are also a human factors problem, although not as severe as the much larger diameter objectives used with the night sights.